This is a tragic news. two midfielders and one defender all of them are quality players. Their absence will affect the team and that is very bad if they can't win their next game after drawing to Brighton. Don't forget that Decaknd Rice a defensive midfielder had a red card in the last match and won't be playing also in the upcoming one. This is a lot of loss for Arsenal at this early stage in the league.
Arsenal against Tottenham is a very strong game. They have to win that game. However, there will be a reshuffle in the players. Jurrnie Timber will substitute for Odegard's position. Thomas Partey will hold the defensive midfield alongside Jorginho. This will work well for the team and if they can keep the play on till the game is over.
Havertz and Trossard might likely rotate to midfielder positions, but this will make them have no player to back up on striker positions. Arsenal need to use all of their players, unfortunately they can't sign more players since the transfer window was closed.
The match will held in Tottenham stadium, this gives more disadvantage to Arsenal.
Considering Tottenham isn't in shape, I guess the match will end in draw.